The present invention relates in general to blood filtration, and more specifically to a blood filter that is removable.
Deep vein thrombosis is a condition in which a blood clot, called a thrombus, develops in the vein of a patient. The thrombus or a portion of it may break off, in which case it is called an embolus, travel through the venous system and become lodged in the patient""s heart or lungs. Emboli lodged in the lungs, a condition termed pulmonary embolism, are potentially dangerous because the emboli may obstruct the arteries of the lung and lead to death.
It is estimated that deep vein thrombosis afflicts approximately 200,000 people every year. Deep vein thrombosis and pulmonary embolism most often occur in bedridden patients, but may also occur in ambulatory or otherwise healthy people. Deep vein thrombosis is a major complication for orthopedic surgical patients, such as those who have undergone major hip or knee surgery and for patients suffering from cancer or other chronic illnesses.
One study estimated that 600,000 people develop pulmonary emboli each year and it proves fatal for 90,000 of them. (See, Vascular Surgery Principles and Practice, Samuel Wilson, et al., Ch. 59, 3rd Ed. 1996). Patients suffering from deep vein thrombosis and/or pulmonary embolism are typically treated with an initial course of intravenous anticoagulant, such as heparin, followed by a course of oral anticoagulant to try to dissolve the thrombi and/or emboli. However, anticoagulant therapy may not always be completely effective for some patients, and may be contraindicated in other patients, so that for those patients other measures must be employed.
A common treatment option for patients with deep vein thrombosis and/or pulmonary embolism, where anticoagulant therapy has not been completely effective or is contraindicated, is the surgical insertion of a blood filter into a large blood vessel such as the vena cava. The inferior vena cava is a large vein that empties blood into the heart received from the legs and lower abdominal area. The superior vena cava is a large vein that empties blood into the heart received from the head, neck, arms and chest. Vena cava filters can prevent emboli from entering the patient""s heart and lungs by filtering the blood before it returns to the heart. Some vena cava filters are permanently implanted in the patient and remain with them for life. Some newer vena cava filters can be removed if there is no longer an indication for their use.
A significant drawback associated with the use of a removable vena cava filter is that the longer the filter remains in the patient, the greater the chance of tissue growth into and around the filter. This ingrowth can result in blockages forming in the blood vessel at the site of the filter. Such blockages can narrow or occlude the vessel at the region of the filter. Another problem associated with tissue ingrowth is that removal of the vena cava filter can be complicated because the blood vessel may rip or tear as the surgeon attempts to remove the filter that is ingrown with tissue. This problem may be especially pronounced in children treated by vena cava filter implantation, because children are growing and therefore may be more likely to experience rapid tissue ingrowth. Removable vena cava filters have heretofore neglected the problem of tissue ingrowth.
Therefore, a need exists in the art for a blood filter which will be removable and which will resist or prevent the ingrowth of tissue thereby facilitating easier removal from the blood vessel.
The present invention provides such a blood filter, which can reduce the occurrence of circulatory occlusions, including pulmonary emboli, in patients and can easily be removed from the venous system of the patient where there is no longer an indication for its use.
The present invention provides a blood filter comprising a plurality of central struts, the distal ends thereof intersecting at a vertex, a hollow tubular member having distal and proximal ends in fluid communication, and having at least one vertical strut extending therefrom, and means for retaining the plurality of central struts within the hollow tubular member.
The present invention further provides a blood filter comprising a plurality of central struts, the distal ends thereof intersecting at a vertex, and a hollow tubular member having distal and proximal ends in fluid communication, with at least one vertical strut extending therefrom, wherein the plurality of central struts are retained within the hollow tubular member.
The present invention yet further provides a method of using a blood filter to reduce circulatory occlusion in a patient, the blood filter comprising a plurality of central struts, the distal ends thereof intersecting at a vertex and a hollow tubular member having distal and proximal ends in fluid communication, with at least one vertical strut extending therefrom, wherein the plurality of central struts are retained within the hollow tubular member, the method comprising, surgically implanting the blood filter into a blood vessel of the patient such that the hollow tubular member lies adjacent to the inner wall of the blood vessel and such that blood flows through the filter
The present invention still further provides a method of using a blood filter to reduce circulatory occlusion in a patient, the blood filter comprising a plurality of central struts, the distal ends thereof intersecting at a vertex, a hollow tubular member having distal and proximal ends in fluid communication, and having at least one vertical strut extending therefrom, and means for retaining the plurality of central struts within the hollow tubular member, the method comprising, surgically implanting the blood filter into a blood vessel of the patient such that the hollow tubular member lies adjacent to the inner wall of the blood vessel and such that blood flows through the filter.
The present invention also provides a method of using at least one blood filter to reduce circulatory occlusion in a patient, the at least one blood filter comprising a plurality of central struts, the distal ends thereof intersecting at a vertex, a hollow tubular member having distal and proximal ends in fluid communication with at least one vertical strut extending therefrom, and a means for retaining the plurality of central struts within the hollow tubular member, the method comprising, surgically implanting at least one blood filter into at least one blood vessel of the patient such that blood flows through the at least one blood filter and such that the hollow tubular member lies adjacent to the wall of the at least one blood vessel.
These and other advantages and benefits of the present invention will be apparent from the Detailed Description of the Invention herein below.